It's always interesting to speculate on the reason for these apparitions. They are almost invariably related to violent episodes and very often warfare. The Liverpool Echo article says a ghost was seen wearing "a WWI uniform". That's a good clue to its association (you don't have to even believe in the supernatural to believe in the reality of this phenomenon; the examples are endless, from Hessian soldiers haunting Dutch communities in the US to the Loch Ness Monster appearing in 1933).